As the guardians of Japan's revered national sport, sumo wrestlers are used to their share of pushing and shoving. But now it is sumo itself that is taking a very public battering.

Weeks after Asashoryu, one of only two reigning grand champions, angered sumo authorities by playing football while supposedly injured, police have launched an investigation into the sudden death of a teenage recruit, allegedly at the hands of his stable master and fellow wrestlers.

Takashi Saito, who fought under the name Tokitaizan, collapsed during a morning training session in June and died in hospital a few hours later. He had been forced to push a succession of heavier stablemates across the ring for 30 minutes without a break, a routine that witnesses say left him in obvious distress.

Saito was clearly unhappy with the life of a junior sumo wrestler. He had run away at least twice, telling his father during a final, tearful telephone call that he was scared of the senior wrestlers with whom he trained, ate and slept.

His stable master, Tokitsukaze, has admitted smashing him over the head with a beer bottle as punishment for his most recent escape attempt. Later, several of his stablemates allegedly beat him with a steel baseball bat in an attempt to administer "tough love". When his family were sent his body they found it covered in unexplained cuts, bruises and cigarette burns.

Concerned by the damage the death is inflicting on the 2,000-year-old sport, the government has launched an investigation and ordered sumo to review its brutal training methods.

Sumo's elders must yearn for the days when the sport's biggest problems were dwindling attendances and the absence of a home-grown grand champion, or yokozuna. Both of the current yokozuna are Mongolian, but sumo fans won't see Asashoryu in the ring at the next tournament in November. The undisputed bad boy of sumo was banned for two tournaments for his infamous appearance, in a Wayne Rooney shirt, in a charity football match in Mongolia, days after he pulled out of an exhibition tour with a serious injury.

Traditionalists will disagree, but sumo is dull without him. Accusations of match-fixing, bullying and violence have clouded sumo for some time, leading to a dramatic drop in interest among school-leavers. If potential grand champions of the future are not to be lost to rugby, judo and baseball, sumo needs a quick return to the days when the biggest scandal was Asashoryu's larger-than-life antics.